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Aperture
Kinds of Aperture Terms modified by Aperture Selected AbstractsEyelid Tightening and Improved Eyelid Aperture through Nonablative Fractional ResurfacingDERMATOLOGIC SURGERY, Issue 11 2008SEAN A. SUKAL MD BACKGROUND AND OBJECTIVE The effects of fractional resurfacing on eyelid tightening and aperture are unknown. Our purpose was to retrospectively examine the potential for eyelid tightening and eye-aperture opening in patients treated with nonablative fractional resurfacing for facial photorejuvenation. STUDY DESIGN/MATERIALS AND METHODS Fractional laser treatments using a 1,550-nm erbium-doped fiber laser system on the upper and lower eyelids were given at a pulse energy of 17 to 20 mJ at 125 micro-thermal zones (MTZ)/cm2 to a final density of 500 to 750 MTZ/cm2. Each patient had 3 to 7 treatments. Standard pre- and post-treatment photographs were taken at each visit. Physicians who graded 31 preselected patient photographs using a 4-point scale evaluated eyelid tightening. Increase in eyelid aperture was also evaluated. RESULTS All patients had some degree of eyelid tightening; 19% achieved 1% to 25% tightening, 26% achieved 25% to 50%, 26% achieved 50% to 75%, and 29% achieved 75% to 100%. Increase in eyelid aperture was seen in 55.9% of patients. Postoperative wounding, hypopigmentation, hyperpigmentation, persistent erythema, and scarring were not observed. All patients experienced mild or no edema for a few days after treatment. CONCLUSION Fractional resurfacing tightens and increases eyelid aperture without wounding, downtime, or long-term complications. [source] Detection of artificially induced vertical radicular fractures using Tuned Aperture Computed TomographyEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 6 2001Madhu K. Nair This study compared the accuracy of three imaging modalities for the detection of artificially induced vertical root fractures (VRF) on teeth in cadaver mandibles. Fifty-four single-rooted, endodontically treated mandibular teeth being prepared to carry posts were evaluated using direct digital radiography (DDI) with a Schick sensor, unprocessed Tuned Aperture Computed Tomography® (TACT-U) images and iteratively restored TACT (TACT-IR) images. Twenty-eight of these teeth had been subjected to fracture induction using an apically driven force. Nine basis images were used for each TACT image generation. Eight observers used a five-point confidence rating scale to record the confidence with which they considered a fracture to be present or not. Sensitivity and specificity values were computed and receiver operating characteristic (ROC) curves were generated. The areas under the curves (Az) used as an indication of the diagnostic accuracy of the imaging system were as follows: DDI: 0.37; TACT-U: 0.77 and TACT-IR: 0.81. DDI was significantly inferior to the TACT modalities. Differences in detection efficacy based on observers and observation sessions were noted on ANOVA and post-hoc Tukey's tests. This study indicates that TACT is the imaging modality of choice for VRF in endodontically treated teeth. [source] Fabrication of near-field optical apertures in aluminium by a highly selective corrosion process in the evanescent fieldJOURNAL OF MICROSCOPY, Issue 3 2003D. Haefliger Summary A simple, one-step process to fabricate high-quality apertures for scanning near-field optical microscope probes based on aluminium-coated silicon nitride cantilevers is presented. A thin evanescent optical field at a glass,water interface was used to heat the aluminium at the tip apex due to light absorption. The heat induced a breakdown of the passivating oxide layer and local corrosion of the metal, which selectively exposed the front-most part of the probe tip from the aluminium. Apertures with a protruding silicon nitride tip up to 72 nm in height were fabricated. The height of the protrusion was controlled by the extent of the evanescent field, whereas the diameter depended on the geometry of the probe substrate. The corrosion process proved to be self-terminating, yielding highly reproducible tip heights. Near-field optical resolution in a transmission mode of 85 nm was demonstrated. [source] A novel silicon patch-clamp chip permits high-fidelity recording of ion channel activity from functionally defined neuronsBIOTECHNOLOGY & BIOENGINEERING, Issue 4 2010Christophe Py Abstract We report on a simple and high-yield manufacturing process for silicon planar patch-clamp chips, which allow low capacitance and series resistance from individually identified cultured neurons. Apertures are etched in a high-quality silicon nitride film on a silicon wafer; wells are opened on the backside of the wafer by wet etching and passivated by a thick deposited silicon dioxide film to reduce the capacitance of the chip and to facilitate the formation of a high-impedance cell to aperture seal. The chip surface is suitable for culture of neurons over a small orifice in the substrate with minimal leak current. Collectively, these features enable high-fidelity electrophysiological recording of transmembrane currents resulting from ion channel activity in cultured neurons. Using cultured Lymnaea neurons we demonstrate whole-cell current recordings obtained from a voltage-clamp stimulation protocol, and in current-clamp mode we report action potentials stimulated by membrane depolarization steps. Despite the relatively large size of these neurons, good temporal and spatial control of cell membrane voltage was evident. To our knowledge this is the first report of recording of ion channel activity and action potentials from neurons cultured directly on a planar patch-clamp chip. This interrogation platform has enormous potential as a novel tool to readily provide high-information content during pharmaceutical assays to investigate in vitro models of disease, as well as neuronal physiology and synaptic plasticity. Biotechnol. Bioeng. 2010;107:593,600. © 2010 Wiley Periodicals, Inc. [source] Why does some pollen lack apertures?BOTANICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2007A review of inaperturate pollen in eudicots Apertures are key characters of pollen grains with systematic importance in angiosperms. They function as sites for pollen tube exit, water uptake, transfer of recognition substances and accommodation of volume changes. Not all pollen has apertures; inaperturate pollen (lacking obvious apertures) characterizes many angiosperm groups, especially in early divergent angiosperms and monocots, but also eudicots. In order to expand our knowledge of the systematic distribution, possible functional significance and development of inaperturate pollen in angiosperms, this review focuses on inaperturate and cryptoaperturate (with hidden apertures) pollen in the large eudicot clade, which comprises about 75% of present-day angiosperm species. It includes new TEM observations of inaperturate pollen from four exemplar taxa selected from different parts of the eudicot phylogeny. Two categories of inaperturate (including cryptoaperturate) pollen occur in eudicots. (1) Sterile attractant or feeding pollen associated with functional dioecy has evolved iteratively at least six times in conjunction with complex breeding systems in the core eudicots. (2) Fertile pollen has evolved numerous times independently throughout eudicots, though generally in a relatively small number of individual taxa. Notable exceptions are the petaliferous crotonoid Euphorbiaceae s.s., in which fertile inaperturate pollen occurs in c. 1500 species, and two subfamilies of Apocynaceae s.l. (Secamonoideae and Asclepiadoideae) with c. 2500 species with fertile inaperturate pollen in pollinia. Fertile inaperturate pollen is sometimes (but not always) associated with an aquatic habit, parasitism, insectivory, heterostyly, anemophily or pollinia. Most fertile inaperturate pollen has a thin exine, or the exine is largely restricted to isolated components (muri, protuberances, subunits) separated by thinner areas which probably function as apertures. In cryptoaperturate pollen, the aperture is covered by continuous exine which probably has a protective function, similar to an operculum. Developmentally, inaperturate pollen is not associated with any particular tetrad type or meiotic spindle orientation (unlike some apertures) due to the absence of a colpal shield of endoplasmic reticulum or other organelles and hence is independent of microsporogenesis type. The lack of a colpal shield during the tetrad stage of development permits complete deposition of first primexine and then exine around each microspore, possibly mediated by the action of the DEX1 protein. © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society, 2007, 155, 29,48. [source] Reinterpretable Imager: Towards Variable Post-Capture Space, Angle and Time Resolution in PhotographyCOMPUTER GRAPHICS FORUM, Issue 2 2010Amit Agrawal Abstract We describe a novel multiplexing approach to achieve tradeoffs in space, angle and time resolution in photography. We explore the problem of mapping useful subsets of time-varying 4D lightfields in a single snapshot. Our design is based on using a dynamic mask in the aperture and a static mask close to the sensor. The key idea is to exploit scene-specific redundancy along spatial, angular and temporal dimensions and to provide a programmable or variable resolution tradeoff among these dimensions. This allows a user to reinterpret the single captured photo as either a high spatial resolution image, a refocusable image stack or a video for different parts of the scene in post-processing. A lightfield camera or a video camera forces a-priori choice in space-angle-time resolution. We demonstrate a single prototype which provides flexible post-capture abilities not possible using either a single-shot lightfield camera or a multi-frame video camera. We show several novel results including digital refocusing on objects moving in depth and capturing multiple facial expressions in a single photo. [source] Eyelid Tightening and Improved Eyelid Aperture through Nonablative Fractional ResurfacingDERMATOLOGIC SURGERY, Issue 11 2008SEAN A. SUKAL MD BACKGROUND AND OBJECTIVE The effects of fractional resurfacing on eyelid tightening and aperture are unknown. Our purpose was to retrospectively examine the potential for eyelid tightening and eye-aperture opening in patients treated with nonablative fractional resurfacing for facial photorejuvenation. STUDY DESIGN/MATERIALS AND METHODS Fractional laser treatments using a 1,550-nm erbium-doped fiber laser system on the upper and lower eyelids were given at a pulse energy of 17 to 20 mJ at 125 micro-thermal zones (MTZ)/cm2 to a final density of 500 to 750 MTZ/cm2. Each patient had 3 to 7 treatments. Standard pre- and post-treatment photographs were taken at each visit. Physicians who graded 31 preselected patient photographs using a 4-point scale evaluated eyelid tightening. Increase in eyelid aperture was also evaluated. RESULTS All patients had some degree of eyelid tightening; 19% achieved 1% to 25% tightening, 26% achieved 25% to 50%, 26% achieved 50% to 75%, and 29% achieved 75% to 100%. Increase in eyelid aperture was seen in 55.9% of patients. Postoperative wounding, hypopigmentation, hyperpigmentation, persistent erythema, and scarring were not observed. All patients experienced mild or no edema for a few days after treatment. CONCLUSION Fractional resurfacing tightens and increases eyelid aperture without wounding, downtime, or long-term complications. [source] The Effect of Full-Face Broadband Light Treatments Alone and in Combination With Bilateral Crow's Feet Botulinum Toxin Type A ChemodenervationDERMATOLOGIC SURGERY, Issue 3 2004Jean Carruthers MD Background. Broadband light (BBL; Intense Pulsed Light; Lumenis Ltd., Yokneam, Israel) is a powerful, nonablative, light-based technology that targets melanin and hemoglobin and stimulates the formation of collagen and elastin. Botulinum toxin type A (BTX-A; BOTOX; Allergan Inc., Irvine, CA) treatment of the lateral periocular region relaxes the vertical fibers of the orbicularis oculi and results in softening of the lateral orbital crow's feet rhytides and widening of the palpebral aperture. Objective. To compare the effects of full-face BBL in combination with BTX-A and BBL alone in female subjects with Fitzpatrick I,III skin types, Glogau II,III rhytides, and significant associated facial lentigines and telangiectasia. Methods. This was a prospective, randomized study of 30 women with moderate to severe crow's feet rhytides. Half of the subjects were treated with BTX-A and BBL and the other half with BBL alone. Their response was assessed clinically and photographically. Skin biopsies of the temporal skin were taken from two subjects in each group and were stained with Masson trichrome. Results. Patients treated with a combination of BTX-A and BBL experienced a better response to treatment, both at rest and on maximum smile, as well as a slightly improved response in associated lentigines, telangiectasia, pore size, and facial skin texture compared with patients who received BBL treatment alone. Skin biopsies showed an increase in dermal collagen in each group. Conclusions. The patients in this study benefited from both treatments. Although BBL led to a remarkable improvement in full-face telangiectasias, lentigines, and skin texture, the improvement increased in all categories with combination therapy. In addition, an added improvement in the full-face aesthetic with both BTX-A and BBL therapy combined was obvious. These results suggest that both treatments,although evidently complementary,may also act synergistically to produce optimal clinical effects, revolutionizing the treatment of facial aging. [source] Botulinum-A Toxin Treatment of the Lower Eyelid Improves Infraorbital Rhytides and Widens the EyeDERMATOLOGIC SURGERY, Issue 8 2001Timothy Corcoran Flynn MD Botulinum-A exotoxin (BTX-A) can be used cosmetically to improve rhytides, particularly of the upper one-third of the face. In this study, fifteen women had BTX-A (BOTOX, Allergan, Inc.) injected into the orbicularis oculi muscle. One lower eyelid received two units just subdermally in the midpupillary line three millimeters below the ciliary margin. The opposite periocular area received two units BTX-A in the lower eyelid with 12 units BTX-A injected into the lateral orbital ("crow's foot") area. Three injections of four units each were placed 1.5 cm from the lateral canthus, each 1 cm apart. Patients and physicians independently evaluated the degree of improvement (grade 0 = no improvement, grade 1 = mild improvement, grade 2 = moderate improvement, and grade 3 = dramatic improvement). An independent photographic analysis was performed. Patients reported a grade of 0.73 when two units were injected alone into the lower lid, and a grade of 1.9 when the lower eyelid and the lateral orbital areas were injected. Physician assessment was grade 0.7 with injection of the eyelid alone and grade 1.8 with injection of the lower eyelid and lateral orbital area. Single investigator photographic analysis demonstrated that 40% of the subjects who had injection of the lower eyelid alone had an increased palpebral aperture (IPA), while 86% of the subjects who had injection of the lower eyelid and lateral orbital area had an IPA. Subjects receiving two units alone had an average 0.5 mm IPA and a mean 1.3 mm IPA at full smile. Concomitant treatment of the lateral orbital area produced a mean 1.8 mm IPA at rest and a mean 2.9 mm IPA at full smile. The results were more notable in the Asian eye. Two units of BTX-A injected into the lower eyelid orbicularis oculi muscle improves infraorbital wrinkles, particularly when used in combination with BTX-A treatment of the lateral orbital area. [source] Laparoscopic paraesophageal hernia repair: quality of life outcomes in the elderlyDISEASES OF THE ESOPHAGUS, Issue 8 2008E. J. Hazebroek SUMMARY Paraesophageal hernias (PEH) occur when there is herniation of the stomach through a dilated hiatal aperture. These hernias occur more commonly in the elderly, who are often not offered surgery despite the failure of medical treatment to address mechanical symptoms and life-threatening complications. The aim of this study was to assess the impact of laparoscopic repair of PEH on quality of life in an elderly population. Data were collected prospectively on 35 consecutive patients aged >70 years who had laparoscopic repair of a symptomatic PEH between December 2001 and September 2005. The change in quality of life was assessed using a validated questionnaire, the Quality of Life in Reflux and Dyspepsia questionnaire (QOLRAD), and by patient interviews. Patients were assessed preoperatively, and at 6 weeks, 6 months, 12 months, 1 year, and 2 years postoperatively. Mean patient age was 77 years (range 70,85); mean American Society of Anesthesiologists class was 2.7 (range 1,3). There were 28 women and 7 men. There was one readmission for acute reherniation, which required open revision. Total complication rate was 17.1%. All complications were treated without residual disability. There was no 30-day mortality, and median hospital stay was 3 days (range 2,14). Completed questionnaires were obtained in 30 of 35 patients (85.7%). There was a significant improvement in quality of life, as measured with QOLRAD, at all postoperative time points (P < 0.001). Laparoscopic PEH repair can be performed with acceptable morbidity in symptomatic patients refractory to conservative treatment and is associated with a significant improvement in quality of life. Our data support elective repair of symptomatic PEH in the elderly, a population who may not always be referred for a surgical opinion. [source] Genital system anatomy and development of Ovatella myosotis by three-dimensional computer visualizationACTA ZOOLOGICA, Issue 2 2009Bernhard Ruthensteiner Abstract Adult anatomy as well as organogenesis of the genital system of the ellobiid pulmonate Ovatella myosotis is investigated in detail by means of serial sectioning and three-dimensional computer reconstruction and visualization. From the middle portion of the adult, which has four nidamental glands, a spermoviduct leads to a common genital aperture. From here two separate structures, the vas deferens and a groove on the body surface, lead anteriorly. The latter is termed the egg groove because it carries the egg ribbon anteriorly, a function that is recognized here for the first time in the Ellobiidae. The evolution of this structure is discussed. In development, the organ system arises from four separate anlagen: (1) the ovotestis anlage, (2) the pallial anlage giving rise to the hermaphrodite duct, fertilization pouch,spermatheca complex, nidamental glandular complex and spermoviduct, (3) the bursa copulatrix anlage and (4) the anlage of the copulatory organ, vas deferens and egg groove. This development mode strongly resembles that of the siphonariid Williamia radiata, supporting its interpretation as a plesiomorphy in Pulmonata. Similarities in development of primitive pulmonates and evolution in gastropods lead to the assumption that ontogenesis of this organ system reflects evolution to some degree. [source] Morphometry and sexual dimorphism of the coastal spotted dolphin, Stenella attenuata graffmani, from Bahía de Banderas, MexicoACTA ZOOLOGICA, Issue 4 2004Laura Sanvicente-Añorve Abstract External measurements and size differences between the sexes were examined in the coastal spotted dolphin, Stenella attenuata graffmani, in Bahía de Banderas, on the Mexican Pacific coast. The dolphins were collected by local fishermen and 29 external characteristics were measured by members of the Marine Mammals Laboratory, University of Mexico. The length of each characteristic with respect to total length was analysed through adjustment of the data to a power equation. A stepwise discriminant analysis was applied to the absolute values and to those expressed as proportions to analyse the differences between the sexes. Results indicate that growth in these dolphins is generally negatively allometric, and most of the characteristics measured were, in both absolute and proportional terms, greater in male dolphins than in female dolphins. As found in many species of odontocetes, the discriminant analysis showed that the main differences between the sexes for this coastal subspecies include the relative positions of the umbilicus, the genital aperture and the anus. The morphometric data provided by this study, corresponding to 29 specimens of S. a. graffmani collected in a restricted locality of the Mexican Pacific coast, are particularly interesting to studies documenting latitudinal morphological differences in the coastal spotted dolphin. [source] RELATIVE ROLE OF GENETIC DETERMINATION AND PLASTIC RESPONSE DURING ONTOGENY FOR SHELL-SHAPE TRAITS SUBJECTED TO DIVERSIFYING SELECTIONEVOLUTION, Issue 5 2009Paula Conde-Padín We studied the relative role of genetic determination versus plastic response for traits involved in ecological adaptation of two ecotypes of Littorina saxatilis living at different shore levels. To investigate the magnitude of the plastic response across ontogeny, we compared morphological data from individuals grown in the laboratory and taken from the wild at three developmental stages: shelled embryos, juveniles, and adults. The results indicate that most shell shape variation (72,99%) in adaptive traits (globosity and aperture of the shell) is explained by the ecotype irrespective of the growth environment, suggesting that direct genetic determination is the main factor responsible for the process of adaptation in the wild. There was a tendency for the contribution of plasticity to increase over ontogeny but, in general, the direction of the plastic response did not suggest that this was adaptive. [source] Physical apertures as constraints on egg size and shape in the Common Musk Turtle, Sternotherus odoratusFUNCTIONAL ECOLOGY, Issue 1 2001P. J. Clark Summary 1,Egg size in turtles often increases with female size, contrary to expectations of optimality. Functional constraints on egg width imposed by the pelvic aperture or the gap between the carapace and plastron (the caudal gap) have been inferred for a few populations but appear inapplicable in others. 2,For Sternotherus odoratus (the Common Musk Turtle), the pelvic aperture was always wider than the width of the female's largest egg by at least 3·7 mm. The caudal gap was narrower than the widest egg for 25·7% of the females. 3,Egg width increased, and elongation (length/width) decreased, as female size and clutch size increased. 4,Females at three ecologically contrasting sites differed appreciably in size but produced eggs of the same mean shape and size, despite the strong within-site changes in both egg size and shape with female size. As the younger females at all sites were of similar age and produced eggs of similar size and shape (again, despite differences in body size), egg size and shape may be age-specific. 5,No optimal egg size prevailed but the scaled residuals of egg size with female mass were less variable than were those for clutch size. [source] From Micro to Meso: an exercise in determining hydraulic conductivity of fractured sandstone cores from detailed characterization of the fracturesGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 3 2006Salima Baraka-Lokmane SUMMARY Hydraulic conductivities of fractured sandstone bore cores of 0.1 m in diameter are calculated using detailed characterization of the fracture geometry parameters determined using a resin casting technique. The accuracy of the measurements was about 0.25,1.25 ,m with the image size used. The values of the effective fracture apertures vary between 10 ,m and 50 ,m. For modelling purposes the samples are sectioned serially, perpendicular to the flow direction along the cylinder axis. The hydraulic conductivity of individual slices is estimated by summing the contribution of the matrix (assumed uniform) and each fracture (depending on its length and aperture). Finally, the hydraulic conductivity of the bulk sample is estimated by a harmonic average in series along the flow path. Results of this geometrical upscaling compare favourably with actual conductivity measured in hydraulic and pneumatic experiments carried out prior to sectioning. This study shows that the determination of larger-scale conductivity can be achieved, based on the evaluation of fracture geometry parameters (e.g. fracture aperture, fracture width and fracture length), measured using an optical method, at least at the laboratory scale. [source] Crustal structure deduced from receiver functions via single-scattering migrationGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2002E. Bertrand Summary An investigation of the teleseismic P -wave coda is performed using the single-scattering approximation. The method allows one to image short-wavelength scale (,2 km) velocity and density heterogeneities and structures that are barely detected by traveltime tomography. Source effects are removed by using receiver functions for data interpretation, but the amplitude (especially the sign of the signal) is synthesized. Both broad-band seismological stations in the southwestern Alps (France) and Campanian plain (Italy) are used for the illustration of the proposed method. Because of the large aperture of our arrays, laterally small-scale heterogeneities are difficult to image and we must assume lateral continuity of the detectable structure. If so, we show that this depth migration based on a single-scattering approach can recover both the depth and the geometry of the main discontinuities below the studied areas. In the southwestern Alps, we underline a complex crustal structure and Moho dipping topography. The Moho depth increases from 20 to 30 km between the coastline and the Mercantour range. In the Campanian plain (surrounding Mount Vesuvius) we also find a southeastwards-dipping Moho. Furthermore, the three main discontinuities are imaged, showing a relatively shallow mantle,crust discontinuity and a deeper one near the coastline. [source] Influence of Small-Scale Heterogeneities on Contaminant Transport in Fractured Crystalline RockGROUND WATER, Issue 5 2006Ralph Mettier We present a sequence of purely advective transport models that demonstrate the influence of small-scale geometric inhomogeneities on contaminant transport in fractured crystalline rock. Special weight is placed on the role of statistically generated variable fracture apertures. The fracture network geometry and the aperture distribution are based on information from an in situ radionuclide retardation experiment performed at Grimsel test site (Swiss Alps). The obtained breakthrough curves are fitted with the advection dispersion equation and continuous-time random walks (CTRW). CTRW is found to provide superior fits to the late-arrival tailing and is also found to show a good correlation with the velocity distributions obtained from the hydraulic models. The impact of small-scale heterogeneities, both in fracture geometry and aperture, on transport is shown to be considerable. [source] Analysis of a Vertical Dipole Tracer Test in Highly Fractured RockGROUND WATER, Issue 5 2002William E. Sanford The results of a vertical dipole tracer experiment performed in highly fractured rocks of the Clare Valley, South Australia, are presented. The injection and withdrawal piezometers were both screened over 3 m and were separated by 6 m (midpoint to midpoint). Due to the long screen length, several fracture sets were intersected, some of which do not connect the two piezometers. Dissolved helium and bromide were injected into the dipole flow field for 75 minutes, followed by an additional 510 minutes of flushing. The breakthrough of helium was retarded relative to bromide, as was expected due to the greater aqueous diffusion coefficient of helium. Also, only 25% of the total mass injected of both tracers was recovered. Modeling of the tracer transport was accomplished using an analytical one-dimensional flow and transport model for flow through a fracture with diffusion into the matrix. The assumptions made include: streamlines connecting the injection and withdrawal point can be modeled as a dipole of equal strength, flow along each streamline is one dimensional, and there is a constant Peclet number for each streamline. In contrast to many other field tracer studies performed in fractured rock, the actual travel length between piezometers was not known. Modeling was accomplished by fitting the characteristics of the tracer breakthrough curves (BTCs), such as arrival times of the peak concentration and the center of mass. The important steps were to determine the fracture aperture (240 ,m) based on the parameters that influence the rate of matrix diffusion (this controls the arrival time of the peak concentration); estimating the travel distance (11 m) by fitting the time of arrival of the centers of mass of the tracers; and estimating fracture dispersivity (0.5 m) by fitting the times that the inflection points occurred on the front and back limbs of the BTCs. This method works even though there was dilution in the withdrawal well, the amount of which can be estimated by determining the value that the modeled concentrations need to be reduced to fit the data (,50%). The use of two tracers with different diffusion coefficients was not necessary, but it provides important checks in the modeling process because the apparent retardation between the two tracers is evidence of matrix diffusion and the BTCs of both tracers need to be accurately modeled by the best fit parameters. [source] Interpretation of the enhancement of field-scale effective matrix diffusion coefficient in a single fracture using a semi-analytical power series solutionHYDROLOGICAL PROCESSES, Issue 6 2009Tai-Sheng Liou Abstract A power series solution for convergent radial transport in a single fracture (PCRTSF) is developed. Transport processes considered in PCRTSF include advection and hydrodynamic dispersion in the fracture, molecular diffusion in the matrix, diffusive mass exchange across the fracture-matrix interface, and mixing effects in the injection and the extraction boreholes. An analytical solution in terms of a power series in Laplace domain is developed first, which is then numerically inverted by de-Hoog et al.'s algorithm. Four dimensionless parameters determine the behaviour of a breakthrough curve (BTC) calculated by PCRTSF, which are, in the order of decreasing sensitivity, the matrix diffusion factor, two mixing factors, and the Peclet number. The first parameter is lumped from matrix porosity, effective matrix diffusion coefficient, fracture aperture, and retardation factors. Its value increases as the matrix diffusion effect becomes significant. A non-zero matrix diffusion factor results in a , 3/2 slope of the tail of a log,log BTC, a common property for tracer diffusion into an infinite matrix. Both mixing factors have equal effects on BTC characteristics. However, the Peclet number has virtually no effect on BTC tail. PCRTSF is applied to re-analyse two published test results that were obtained from convergent radial tracer tests in a discrete, horizontal fracture in Silurian dolomite. PCRTSF is able to fit the field BTCs better than the original channel model does if a large matrix diffusion coefficient is used. Noticeably, the ratio of field-scale to lab-scale matrix diffusion coefficients can be as large as 378. This enhancement of the field-scale matrix diffusion coefficient may be ascribed to the presence of a degraded zone at the fracture-matrix interface because of karstic effects, or to flow channeling as a result of aperture heterogeneity. Copyright © 2009 John Wiley & Sons, Ltd. [source] Influences of meteorological and vegetational factors on the partitioning of the energy of a rice paddy fieldHYDROLOGICAL PROCESSES, Issue 8 2005Hiroki Oue Abstract Observations made in a paddy field were analysed to show the influences of meteorological and vegetational factors on the crop's energy budget. Energy budget in the paddy field was characterized by the major partitioning to latent heat flux LE and by the negative Bowen ratio B mostly in the afternoon. Canopy resistance rc, estimated with the Penman,Monteith equation, was related to the influences of solar radiation SR, vapour pressure deficit VPD and plant height. The results demonstrated that rc could not directly account for B but that critical canopy resistance rcc, defined as the canopy resistance when B = 0, could be used to standardize rc, and that rc , rcc proved to be a good parameter to account for B. Influences of bulk stomatal response on energy partitioning were assessed as follows: the Bowen ratio dropped below zero, while the bulk stomatal aperture dwindled with the increase of VPD. In addition, stomata of a big leaf acted to promote the partitioning to LE against the rise of SR in the condition of higher VPD. Copyright © 2004 John Wiley & Sons, Ltd. [source] A three-dimensional integral equation model for calculating poro- and thermoelastic stresses induced by cold water injection into a geothermal reservoirINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 14 2009X. X. Zhou Abstract Poro-mechanical and thermo-mechanical processes change the fracture aperture and thus affect the water flow pattern in the fracture during the cold water injection into enhanced geothermal systems (EGS). In addition, the stresses generated by these processes contribute to the phenomenon of reservoir seismicity. In this paper, we present a three-dimensional (3D) partially coupled poro-thermoelastic model to investigate the poroelastic and thermoelastic effects of cold water injection in EGS. In the model, the lubrication fluid flow and the convective heat transfer in the fracture are modeled by the finite element method, while the pore fluid diffusion and heat conductive transfer in the reservoir matrix are assumed to be 3D and modeled by the boundary integral equation method without the need to discretize the reservoir. The stresses at the fracture surface and in the reservoir matrix are obtained from the numerical model and can be used to assess the variation of in situ stress and induced seismicty with injection/extraction. Application of the model shows that rock cooling induces large tensile stresses and increases fracture conductivity, whereas the rock dilation caused by fluid leakoff decreases fracture aperture and increases compressive total stresses around the injection zone. However, increases in pore pressure reduce the effective stresses and can contribute to rock failure, fracture slip, and microseismic activity. Copyright © 2009 John Wiley & Sons, Ltd. [source] Coupled HM analysis using zero-thickness interface elements with double nodes.INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 18 2008Part I: Theoretical model Abstract In recent years, the authors have proposed a new double-node zero-thickness interface element for diffusion analysis via the finite element method (FEM) (Int. J. Numer. Anal. Meth. Geomech. 2004; 28(9): 947,962). In the present paper, that formulation is combined with an existing mechanical formulation in order to obtain a fully coupled hydro-mechanical (or HM) model applicable to fractured/fracturing geomaterials. Each element (continuum or interface) is formulated in terms of the displacements (u) and the fluid pressure (p) at the nodes. After assembly, a particular expression of the traditional ,u,p' system of coupled equations is obtained, which is highly non-linear due to the strong dependence between the permeability and the aperture of discontinuities. The formulation is valid for both pre-existing and developing discontinuities by using the appropriate constitutive model that relates effective stresses to relative displacements in the interface. The system of coupled equations is solved following two different numerical approaches: staggered and fully coupled. In the latter, the Newton,Raphson method is used, and it is shown that the Jacobian matrix becomes non-symmetric due to the dependence of the discontinuity permeability on the aperture. In the part II companion paper (Int. J. Numer. Anal. Meth. Geomech. 2008; DOI: 10.1002/nag.730), the formulation proposed is verified and illustrated with some application examples. Copyright © 2008 John Wiley & Sons, Ltd. [source] A numerical approach for groundwater flow in unsaturated porous mediaINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 9-10 2006F. Quintana Abstract In this article, a computational tool to simulate groundwater flow in variably saturated non-deformable fractured porous media is presented, which includes a conceptual model to obtain analytical expressions of water retention and hydraulic conductivity curves for fractured hard rocks and a numerical algorithm to solve the Richards equation. To calculate effective saturation and relative hydraulic conductivity curves we adopt the Brooks,Corey model assuming fractal laws for both aperture and number of fractures. A standard Galerkin formulation was employed to solve the Richards' equation together with a Crank,Nicholson scheme with Richardson extrapolation for the time discretization. The main contribution of this paper is to group an analytical model of the authors with a robust numerical algorithm designed to solve adequately the highly non-linear Richards' equation generating a tool for porous media engineering. Copyright © 2006 John Wiley & Sons, Ltd. [source] Integrated Microwave and Optical Scanning Probe for Magnetic Resonance ImagingISRAEL JOURNAL OF CHEMISTRY, Issue 1 2008Fadi Sakran We demonstrate a scanning microwave near-field probe based on a slit aperture that is capable of performing spatially-resolved magnetic resonance measurements in the frequency range of 3,90 GHz. We demonstrate local electron spin resonance (ESR), ferromagnetic resonance (FMR), and spin-wave resonance (SWR) studies on model materials. The probe can serve as a local contactless heater as well. We demonstrate also a further application, a dual microwave/optical near-field probe that can be useful in contactless measurements of photoconductivity and fluorescence under microwave irradiation. [source] Tear-film lipid layer morphology and corneal sensation in the development of blinking in neonates and infantsJOURNAL OF ANATOMY, Issue 3 2005John G. Lawrenson Abstract The aim of the study was to evaluate the role of lipid layer thickness and corneal sensation in the development of blinking in neonates. The study group comprised sixty-four neonates and infants (mean age 27.5 ± 15 (sd) weeks, range 3.4,52) whose mothers were attending a general practice healthy baby clinic. Spontaneous eye-blink activity was determined from digital videographic recordings; tear film lipid layer morphology wasexamined using interference patterns produced by the Keeler TearscopeÔ Plus over a five-point grading scale (higher grades are associated with thick and stable lipid films); corneal sensation threshold was assessed with the Non-Contact Corneal Aesthesiometer (NCCA), using the eye-blink response as an objective indication that the cooling stimulus had been felt; palpebral aperture dimensions were measured using calibrated digital still images of the eye in the primary position. The overall mean spontaneous blink-rate was found to be 3.6 (± 0.3) blinks min,1, and the mean interblink time was 21.6 (± 2.8) s. The lowest blink-rates were observed in the 0,17-week age group (average 2 blinks min,1). The blink-rate showed a highly significant correlation with age (r = 0.46, P < 0.01). The overall mean lipid layer grading was 3.6 (± 0.2 SE) arbitrary units. Higher grades were found in the newborn and the mean grading score reduced with age (P < 0.01). The mean sensation threshold to blink (TTB) was 0.69 (0.04 SE) mbar, which did not differ from a control group of older subjects (P > 0.05). There was a rapid increase in palpebral aperture length and width from birth to 1 year old, with surface area increasing by 50% over the same period. We concluded that the low rate of spontaneous eye blink activity in neonates is associated with a thick stable lipid layer that may be a function of a small palpebral aperture. Furthermore, neonates appear to have the capacity to detect ocular surface cooling, which is a major trigger for spontaneous blinking. [source] Hyoid apparatus and pharynx in the lion (Panthera leo), jaguar (Panthera onca), tiger (Panthera tigris), cheetah (Acinonyx jubatus) and domestic cat (Felis silvestris f. catus)JOURNAL OF ANATOMY, Issue 3 2002G. E. Weissengruber Abstract Structures of the hyoid apparatus, the pharynx and their topographical positions in the lion, tiger, jaguar, cheetah and domestic cat were described in order to determine morphological differences between species or subfamilies of the Felidae. In the lion, tiger and jaguar (species of the subfamily Pantherinae) the Epihyoideum is an elastic ligament lying between the lateral pharyngeal muscles and the Musculus (M.) thyroglossus rather than a bony element like in the cheetah or the domestic cat. The M. thyroglossus was only present in the species of the Pantherinae studied. In the lion and the jaguar the Thyrohyoideum and the thyroid cartilage are connected by an elastic ligament, whereas in the tiger there is a synovial articulation. In adult individuals of the lion, tiger and jaguar the ventral end of the tympanohyal cartilage is rotated and therefore the ventral end of the attached Stylohyoideum lies caudal to the Tympanohyoideum and the cranial base. In newborn jaguars the Apparatus hyoideus shows a similar topographical position as in adult cheetahs or domestic cats. In adult Pantherinae, the Basihyoideum and the attached larynx occupy a descended position: they are situated near the cranial thoracic aperture, the pharyngeal wall and the soft palate are caudally elongated accordingly. In the Pantherinae examined the caudal end of the soft palate lies dorsal to the glottis. Differences in these morphological features between the subfamilies of the Felidae have an influence on specific structural characters of their vocalizations. [source] Image enhancement in ultramicroscopy by improved laser light sheetsJOURNAL OF BIOPHOTONICS, Issue 10-11 2010Saiedeh Saghafi Abstract In the majority of implementations of light sheet microscopy, such as ultramicroscopy, the laser beam illuminating the specimen is truncated by a slit aperture before it is focused to a light sheet by a single cylindrical lens. A light sheet generated in this way can be made very thin near to the focal point, but unfortunately its Rayleigh range is severely limited. This problem can be partially solved by using a smaller slit aperture. However, this also causes a major loss in power, a severe broadening of the beam waist, and thus a significant loss of resolution along the detection axis. We developed improved light-sheet-generation optics, which provide longer Raleigh ranges, whilst retaining beam waists comparable to our standard system with one cylindrical lens. Using the modified system we achieved a marked improvement in the resolution of ultramicroscopy reconstructions of representative biological specimens. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] DEVELOPMENT OF A ROTARY PULVERIZER FOR CASSAVA CAKE IN GARI PRODUCTIONJOURNAL OF FOOD PROCESS ENGINEERING, Issue 6 2008L.A. SANNI ABSTRACT The use of a raffia sieve for pulverizing and sifting cassava cake during gari processing is slow, unhygienic and hazardous. A rotary brush and screen mechanism was developed for the pulverization of cassava cake with a view to eliminate the above-mentioned limitations of the existing methods. Machine performance was measured by comparing the product from the raffia sieve with that from a rotary sifter. The 5-mm screen aperture gave a gari of about the same bulk density with that of the raffia sieve. Although the throughput of the rotary sifter using a 5-mm sieve (227.71 kg/h) was lower than that of a 7-mm sieve (350 kg/h), the uniformity coefficient of 1.72 using the 5-mm sieve compared favorably with that of the raffia sieve. The pulverizing efficiency was higher (81.2%), with the 5-mm sieve than with the 7-mm sieve. The higher pulverizing efficiency of the machine reduces the drudgery associated with the pulverization of pressed cassava cake and improves productivity. PRACTICAL APPLICATIONS This research reduces the drudgery and hazard associated with the pulverization and sifting of cassava cake during gari processing in rural West Africa, where the bulk of the world's gari is being processed manually. [source] Pollen Morphology of Tundra Shrubs and Submarginal Plants from Barrow, AlaskaJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 7 2006Ling-Yu Tang Abstract Investigation of plant morphological features, pollen, and habitat have been made for two shrub species from Barrow, Alaska, namely Dryas integrifolia M. Vahl and Salix rotundifolia Trautv., both of which are endemic to the Arctic floristic area. The former species has small lanceolate or plate leaves, whereas the latter has rounded leaves with distinct veins, rich in vitamin C. Both have dwarf and sprawling habits. Pollen studies showed that the pollen grains of the two species are spheroidal to sub-spheroidal or prolate. The type of aperture was tricolporate; pollen size 26.3,31.3 ,m; ornamentation finely reticulate under a light microscope (LM) and striate-reticulate under a scanning electron microscope (SEM) for D. integrafolia and finely reticulate under the LM and SEM for S. rotundifolia. Comparisons were made between the pollen from the same species from Arctic collections with those from China and Japan. Investigation of pollen morphology of tundra plants can provide significant data for comparative studies of fossil pollen and for the reconstruction of paleovegetation and paleoclimate in the Barrow area. (Managing editor: Ya-Qin Han) [source] Rational design of shape selective separations and catalysis: Lattice relaxation and effective aperture sizeAICHE JOURNAL, Issue 3 2010Chrysanthos E. Gounaris Abstract Gounaris et al. presented a computational method that can be used for the quick screening of zeolite structures and provide predictions regarding which of them have the potential to exhibit high selectivity among a set of molecules of interest. This article builds upon this earlier work and furthers our understanding of diffusion processes in zeolites and other microporous metal oxides. We first present an augmented formulation to account for the flexibility of the zeolitic portal and conduct an analysis to assess the effect of varying the parameters of the associated quadratic potential. We then introduce a methodology to map the energetic landscape, identify all locally optimal conformations, and probabilistically account for the multiplicity of conformers. Finally, we conduct sensitivity analysis on the effective size of the aperture, and show how the methodology can be fine,tuned through experimental observations. A comprehensive database of 290 molecules of industrial interest and a total of 123 different zeolite structures were used in this study. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] | |||||||||||||||||||||||||||||||||||||||||||